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Hot Springs Vista 2004 - Circ pump turning on/off and high limit tripping


Empereol
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I noticed that the circulation pump was starting/stopping last week when the hot tub (Hot Springs Vista 2004) control panel lights (both red and green) were flashing. The tub at this time was ~100℉ as set/expected and when the circ pump was running the flow didn't seem to be impeded. I could see bubbles/flow from the floor screen and there is a line plumbed back to the filter compartment where I could feel water coming in when the circ pump was running.

I called a technician in and he thought the control board needed replacing. I didn't want to go down an expensive path until exhausting other options so I did the following:

  1. Use whirlpool rinse to hopefully help clean any issues that might be hiding in the plumbing.
  2. Drain the hot tub and vacuum out the lines.
  3. Disconnect the circ pump and check for blockages in the surrounding plumbing.
  4. Refill the tub with fresh water which was incredibly cold (probably around 40℉).
  5. Resupplied power and now the LIM OK light would not turn on (red light on control panel blinking). So I assumed the high limit switch might be the culprit.
  6. Replaced the high limit thermistor. Still no LIM OK light (red light still blinking on control panel).
  7. Replaced the control thermistor. Still no LIM OK light (red light still blinking on control panel).
  8. Tried setting the thermistors in a bowl of water to bypass the heater (which at this point I thought may be blocked). And the LIM OK light was now on and no blinking red light on the control panel.
  9. I tried different combinations of new and old thermistors in the heater and it eventually was working fine using the old high limit thermistor and a new control thermistor. At this point, I think I've "solved" it although not confident since why would the new high limit thermistor not work? But the hot tub is now functioning properly with very cold water slowing heating up over night.
  10. The morning after the hot tub is now at ~100℉ and the circulation pump is back to starting and stopping
  11. At some point in the above list I tried jumping the pressure switch. It didn't seem to help/hurt.

So based on the above, I am currently leaning towards it being the circulation pump overheating since it seemed to work fine in cold water which presumably kept it cool enough to continue running without tripping itself. However, that doesn't really explain why I needed to change the thermistors (or why both brand new thermistors didn't work together)... However, I don't have a high limit reset switch and was just cutting power to the tub to reset it. Perhaps it was not getting properly reset and the thermistors were a red herring altogether and they all work just fine.

The circulation pump was replaced around 2 years ago so it's relatively new.

Any thoughts or advice would be very welcome!

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Sounds like the board to me. If you think it's from the circ pump, check voltage to the pump when it has stopped. If you have voltage to the pump and it's not working, it's the pump. If the voltage is off, it's the controls causing it. 

@castletonia, does HS have a summer logic to shut off the circ pump if set temp is lower than actual temp? 

If not, it's the board.

Can you post a pic of the circuit board?

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I don't have a multimeter handy but using a non-contact voltage tester I was getting indication there was voltage even when the pump was off. I placed the tester where the circulation pump black wire connects with the board also where it connects with the fuse below it. Would the mainboard provide less voltage to the pump that would still be picked up by the voltage tester or do you expect it would cut the pump off entirely?

Pictures of the daughterboard... 

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That type of tester is useless for anything in a spa. The board only switches one leg, so voltage is present all the time, but no current flow because no continuity on the circuit.

The dark patch was the black gooey stuff. False alarm. But my bet is still the board. 

Harbor freight has multimeters really cheap, and over half of them work. But even a little analog voltmeter (with a dial reading) would do.

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1 minute ago, RDspaguy said:

That type of tester is useless for anything in a spa. The board only switches one leg, so voltage is present all the time, but no current flow because no continuity on the circuit.

Gotcha. I suspected that might be the case. Figured I would try nonetheless. I'll try and get my hands on a meter and test again.

If it is the board though, do you have any thoughts on why the pump would function normally while heating the tub up to warmer temps? It only seems to malfunction when the temp gets higher.

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Could it be a result of running for long enough to get hot? The board has many components that don't handle heat well, and could be getting hot itself as it runs.

Aside from that, I can think of no reason specifically. But circuit boards don't seem to care what makes sense to me when they crap out.

The fact that you already replaced the thermistors leaves little else. And things turning on and off are usually a sign of a faulty transformer, which is part of the board. The voltage test will tell if it's the pump, but that is very odd behavior for a circ pump. 

I would also check incoming voltage, as a failing breaker could cause this as well. And that could also be related to run time.

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5 hours ago, RDspaguy said:

Sounds like the board to me. If you think it's from the circ pump, check voltage to the pump when it has stopped. If you have voltage to the pump and it's not working, it's the pump. If the voltage is off, it's the controls causing it. 

@castletonia, does HS have a summer logic to shut off the circ pump if set temp is lower than actual temp? 

If not, it's the board.

Can you post a pic of the circuit board?

I don't have much experience with those older IQ2020 control packs so I will have to investigate.  The newer ones do have an actual summer mode that will shut the circulation pump off for 8 hours a day, but the circuit board should know that and not go into protection mode.  As for just shutting the circulation pump off when above temperature, not to my knowledge.  

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24 minutes ago, castletonia said:

I don't have much experience with those older IQ2020 control packs so I will have to investigate.  The newer ones do have an actual summer mode that will shut the circulation pump off for 8 hours a day, but the circuit board should know that and not go into protection mode.  As for just shutting the circulation pump off when above temperature, not to my knowledge.  

According to the manual, I have a summer mode which you describe - Shuts the heater and circ pump off for 8hrs then run for 16hrs, repeating until disabled. The manual does not mention anything in regards to the circ pump shutting off at any water temperature only if the pump itself reaches its thermal limits. 

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Results are in: 
I probed the circ pump and it was reading ~120v the entire time - both when the pump was not running as well as running. And just to be incredibly verbose and make sure I did this correctly, I probed the contact marked WHITE and contact marked BLACK on the CIRC PUMP section of the board (red circles in the below image):
 image.png.a28409099365ffbb62aa9b0f8f2e5389.png

Do you think it's fair to say we have ruled out the board as the culprit and this is more than likely a fault with the circ pump?

Thanks again for your time, help, and advice!

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2 hours ago, tjr said:

Put black lead that is attached to inline fuse holder directly to board. those fuse holders get loose and cause problems. If it continues to not move water when getting proper voltage ,replace pump. 

I checked the voltage from the white lead to the black lead with the blue crimp (the pump side of the fuse) and it was a consistent 120v like when I probed the board (board side of the fuse). I figured if the inline fuse/connection was the problem I'd see a voltage drop, correct?

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You are having intermittent problems with circulation  pump not working. Take the fuse assembly out of the equation to see if it solves the problem,if pump is getting constant 120v and not working it is time for new pump. The pumps have computer chip which helps to self prime impeller that probably went bad. 

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